1. Field of the Invention
Embodiments of the present invention generally relate to semiconductor substrate processing equipment. In particular, the invention relates to apparatus and methods for improving the flow of process gases within a processing chamber.
2. Description of the Related Art
Ultra-large-scale integrated (ULSI) circuits may include more than a million electronic devices (e.g., transistors) that are formed on a semiconductor substrate, such as a silicon (Si) substrate, and cooperate to perform various functions. Examples of electronic devices used in ULSI circuits are complementary metal-oxide-semiconductor (CMOS) field effect transistors. A CMOS transistor has a gate structure comprising a polysilicon gate electrode and gate dielectric, and is disposed between source and drain regions formed in the substrate.
Plasma etching is commonly used in the fabrication of transistors and other electronic devices. However, current plasma processing chambers suffer deficiencies in the injection, flow, and exhaust of process gases. For instance, prior art plasma etching chambers provide a plurality of gas injection nozzles located about the periphery of the chamber and a large exhaust port on one side of the chamber. This prior art configuration of gas injection and exhaust leads to unsymmetrical flow of process gases across the surface of the substrate being processed, non-uniform etching of the substrate, inefficiency in the use of process gas, and ultimately yield loss.
Therefore, there is a need for plasma etch chamber improvements to provide more efficient use of process gases and improve the uniformity of substrate processing.